''Sphaerius'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

s in the family Sphaeriusidae, comprising 18 extant species. It is one of the two extant genera in the family, the other being '' Bezesporum''. They are typically found along the edges of streams and rivers, where they feed on

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

; they occur on all continents except

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. Three species occur in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. The overall form of the beetle is convex, glossy, dark brown or black with some markings possible. The head is prominent, with relatively large eyes set far apart, and

capitate The capitate bone is a bone in the human wrist found in the center of the carpal bone region, located at the distal end of the radius and ulna bones. It articulates with the third metacarpal bone (the middle finger) and forms the third carpomet ...

antennae. Total length ranges from . The beetles occur in a variety of damp environments, including mud, under stones, among plant roots and

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...

, and in mosses in bogs. They store some air underneath their

elytra An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...

. Females produce a single large egg at a time. The family used to be known as "Sphaeriidae", but the name was preoccupied by a family of freshwater

clam Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

s. The name was inappropriately replaced with "Microsporidae" (by changing the genus name to ''Microsporus''), but this act has been superseded by a return to the use of ''Sphaerius'' and a reformation of the family name as Sphaeriusidae. The position of the family within Coleoptera has also changed a number of times.

Species

The genus includes the following 18 extant species, as of 2022: *'' Sphaerius acaroides'' – Europe *'' Sphaerius africanus'' – South Africa *'' Sphaerius alticola'' – Nepal *'' Sphaerius coomani'' – Vietnam *'' Sphaerius gustavlohsei'' – Nepal, India:

Darjeeling Darjeeling (, , ) is a city in the northernmost region of the States and union territories of India, Indian state of West Bengal. Located in the Eastern Himalayas, it has an average elevation of . To the west of Darjeeling lies the Koshi Pr ...

*'' Sphaerius hispanicus'' – France, Spain, Algeria, Tunisia *'' Sphaerius humicola'' – Nepal *'' Sphaerius laeviventris'' – India:

Uttarakhand Uttarakhand (, ), also known as Uttaranchal ( ; List of renamed places in India, the official name until 2007), is a States and union territories of India, state in North India, northern India. The state is bordered by Himachal Pradesh to the n ...

*'' Sphaerius madecassus'' – Madagascar *'' Sphaerius obsoletus'' – Vietnam *'' Sphaerius ovensensis'' – Australia *'' Sphaerius perlaevis'' – Vietnam *'' Sphaerius politus'' – USA: California *'' Sphaerius silvicola'' – Nepal *'' Sphaerius spississimus'' – France:

Corsica Corsica ( , , ; ; ) is an island in the Mediterranean Sea and one of the Regions of France, 18 regions of France. It is the List of islands in the Mediterranean#By area, fourth-largest island in the Mediterranean and lies southeast of the Metro ...

, Italy:

Sardinia Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...

, Israel *'' Sphaerius tesselatus'' – Vietnam *'' Sphaerius texanus'' – USA: Texas *'' Sphaerius tropicus'' – Guatemala Species transferred to '' Bezesporum'': *'' Sphaerius minutus'' – China:

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*'' Sphaerius papulosus'' – Myanmar Species of unclear assignment: *'' Sphaerius cribratus'' – Vietnam *'' Sphaerius favosus'' – Vietnam Species excluded from Sphaeriusidae (actually representatives of

Corylophidae Corylophidae is a family of minute hooded beetles, sometimes called minute fungus beetles, in the superfamily Coccinelloidea. There are about 18 genera and at least 120 described species in Corylophidae. They feed on microfungi such as molds, ...

): *'' "Sphaerius" coenensis'' – Australia *'' "Sphaerius" scutellaris'' – USA

Fossil species

* †'' Sphaerius martini'' –

Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...

, Myanmar,

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

References

External links

Sphaeriusidae
Tree of Life {{Taxonbar, from1=Q606681, from2=Q16209130 Myxophaga Myxophaga genera Extant Cenomanian first appearances Taxa named by Joseph Waltl